I'd suggest you add a connection from Prop p6 to DS1307 pin 7, with a high ohms pullup. The 1 second heartbeat from the RTC can be useful.
That's a nice thought. I'm going to put it off for now, though, until I know for sure that the SPS30 will work well on the I2C bus. If it doesn't, I'll need P6 and P7 for SDA and SCL, so I can use P4 and P5 for serial comms.
The JST cable, at least, is discrete-wire, rather than closely-abutted ribbon conductors. So crosstalk should be less of an issue. And I'm using 4.7K pull-ups. Still, for a 3.3V Vdd, 3.3K pull-ups would be even better. The original I2C spec that called for 4.7K pull-ups was written for a 5V Vdd. To get the same initial pull-up current at 3.3V, you need 3.3K.
When recording CO2 measurements, it's helpful to know if people are present, so the measurements can be correlated with human activity, such as breathing. To that end, I installed a motion sensor in one of my CO2 monitors:
Each record that's saved includes a CO2 reading, temperature, humidity, and a summary of human activity during the recording interval.
BTW, this unit uses the larger Sparkfun 128x160 display. I did this so I could display the date and time. But I have to say the display has been a disappointment. Both the brightness and viewing angles suffer in comparison to the 128x128 display. I probably won't be using it again.
With wildfires raging, particulate pollution is of particular concern. So I bought a Sensirion SPS30 particulate sensor. It's a snazzy little unit that bins particulate sizes in PM1.0, PM2.5, PM4.0, and PM10 particulate sizes for both µg/m3 and particle count per cm3. From the PM2.5 and PM10 mass readings, I can compute the EPA air quality index (AQI) and display it on the screen. Here's a photo of unit's guts:
. . . and of it "fully dressed":
A lot of programming remains to be done. I need to sequence the display of the various readings (CO2, temp, RH, barometer, AQI, time/date), since they don't all fit on the screen at once.
I'm happy with the PCB layout now. It encompasses everything I wanted to do with it. I know some of you expressed an interest in obtaining some for your own use. I'm happy to make bare boards available. Of course, to take advantage of time/date, barometer, and extra EEPROM, you'll have to do some surface-mount soldering. If you can live without those features, everything else is thru-hole. Let me know what you think.
Hi Phil,
Please count me in for a couple of those fabs. As usual you've really come through with this, feature by feature, over the past few months!
-- Tracy
Comments
That's a nice thought. I'm going to put it off for now, though, until I know for sure that the SPS30 will work well on the I2C bus. If it doesn't, I'll need P6 and P7 for SDA and SCL, so I can use P4 and P5 for serial comms.
The JST cable, at least, is discrete-wire, rather than closely-abutted ribbon conductors. So crosstalk should be less of an issue. And I'm using 4.7K pull-ups. Still, for a 3.3V Vdd, 3.3K pull-ups would be even better. The original I2C spec that called for 4.7K pull-ups was written for a 5V Vdd. To get the same initial pull-up current at 3.3V, you need 3.3K.
-Phil
Very interesting project I would be interested in buying a couple of them when you are done with all of the revisions on the circuit board
When recording CO2 measurements, it's helpful to know if people are present, so the measurements can be correlated with human activity, such as breathing. To that end, I installed a motion sensor in one of my CO2 monitors:
Each record that's saved includes a CO2 reading, temperature, humidity, and a summary of human activity during the recording interval.
BTW, this unit uses the larger Sparkfun 128x160 display. I did this so I could display the date and time. But I have to say the display has been a disappointment. Both the brightness and viewing angles suffer in comparison to the 128x128 display. I probably won't be using it again.
With wildfires raging, particulate pollution is of particular concern. So I bought a Sensirion SPS30 particulate sensor. It's a snazzy little unit that bins particulate sizes in PM1.0, PM2.5, PM4.0, and PM10 particulate sizes for both µg/m3 and particle count per cm3. From the PM2.5 and PM10 mass readings, I can compute the EPA air quality index (AQI) and display it on the screen. Here's a photo of unit's guts:
. . . and of it "fully dressed":
A lot of programming remains to be done. I need to sequence the display of the various readings (CO2, temp, RH, barometer, AQI, time/date), since they don't all fit on the screen at once.
I'm happy with the PCB layout now. It encompasses everything I wanted to do with it. I know some of you expressed an interest in obtaining some for your own use. I'm happy to make bare boards available. Of course, to take advantage of time/date, barometer, and extra EEPROM, you'll have to do some surface-mount soldering. If you can live without those features, everything else is thru-hole. Let me know what you think.
Thanks,
-Phil
I've added a driver object for the SPS30 particulate sensor to the top post.
Hi Phil,
Please count me in for a couple of those fabs. As usual you've really come through with this, feature by feature, over the past few months!
-- Tracy